1. Field of the Invention
The present invention relates to a radio-frequency heating balloon catheter and, more particularly, to a radio-frequency balloon catheter for the radio-frequency heating treatment of cardiovascular diseases. More specifically, the present invention relates to a radio-frequency heating balloon catheter provided with a balloon to be brought into close contact with a target lesion for radio-frequency heating for the treatment of cardiac arrhythmia.
2. Description of the Related Art
A known method of electrically coagulating a source of arrhythmia (catheter ablation) uses a catheter provided with a metal tip of 4 mm in size, which serves as an electrode, brings the metal tip into contact with the source of arrhythmia and supplies a radio-frequency current to the metal tip. Although this method is effective when the source is a local, one like a source of WPW syndrome or paroxysmal tachycardia, the method is not so effective when the source is an extensive one like a source of atrial fibrillation, atrial flutter or ventricular tachycardia due to organic heart diseases.
Another method of isolating a wide target part heats the target part electrically by radio-frequency heating using an inflatable balloon. Methods of treating lesions caused by arteriosclerosis as well as sources of arrhythmia proposed in, for example, Jpn. Pat. Nos. 2538375, 2510428 and 2574119 to the applicant of the present invention patent application treat a lesion by bringing an inflatable balloon internally provided with a radio-frequency electrode into contact with tissues, and creating a radio-frequency electric field to heat tissues in contact with the balloon.
The interior of the atrium needs to be cauterized linearly to treat atrial flutter or atrial fibrillation.
It has hitherto been believed that the superior pulmonary veins and the inferior pulmonary veins connected to the left atrium are separated and those four pulmonary veins open individually into the left atrium as shown in FIG. 9 or 10. In forming a block line by linearly cauterizing the interior of the atrium to treat atrial flutter or atrial fibrillation, the edges of the four ostia, i.e., the superior right, the superior left, the inferior right and the inferior left opening, of the pulmonary veins must individually be cauterized. A ablation for individually cauterizing the edges of the four ostia of the pulmonary veins takes much time. Since the thin wall of the pulmonary vein is liable to contract and, consequently, the stenosis of the pulmonary vein is liable to occur when the periphery of the pulmonary vein is cauterized.